Who are we? A question as old as 74,000 years
Lhendup G Bhutia | 23 Dec, 2015
About 74,000 years ago, a major event occurred on earth. A deafening noise ran across the planet as a super-volcano, Toba, erupted on the modern-day island of Sumatra in Indonesia, considered by scientists to be the largest such event on earth in at least the past two million years. The explosion was to spew forth some 2,800 cubic kilometres of magma, equivalent in mass—according to estimates—to about 19 million Empire State Buildings put together, even as the volcano itself collapsed inwards to form a huge sunken caldera (now visible as Lake Toba). The gases it released encircled the globe on air currents. The ash, fanned by winds, spread out to the north and west. When the ash began raining down, it covered the Indian Subcontinent and fell upon oceans as distant as the South China Sea in the east to the Arabian Sea in the west. It blocked the sun and darkened the skies, affected rainfall, probably caused tsunamis, lowered global temperatures, turned lush habitats into wastelands, and plunged the world into what many believe was a volcanic winter. According to one line of evolutionary thought, the event was so catastrophic, it caused a genetic bottleneck in human evolution that almost wiped out all of humanity. Some scientists believe that we modern Homo sapiens are the descendants of only around 1,000-10,000 breeding pairs that were able to survive the event.
For archaeologists interested in human evolution and their exodus from Africa, that alleged near-extinction point became an epochal marker. The prehistoric world became either pre-Toba or post-Toba.
A few years ago, Ravi Korisettar, a well-known Indian archaeologist from Karnatak University in Dharwad, a city about 425 km northwest of Bengaluru, found himself working with a team of international and local archaeologists, trying to unearth clues about India’s earliest human inhabitants. Among this team was Michael Petraglia, an archaeologist and professor of human evolution at the University of Oxford who has spent several years searching for evidence that can solve the riddle of the human exodus from Africa. The researchers started excavating caves, especially those in Andhra Pradesh’s Kurnool district, where discoveries in the past of several stone artefacts, beads and ancient cave drawings have hinted at a rich ancient human presence in this part of the world. “We were revisiting localities noted by geologists and researchers back in the 1970s and 80s, hoping we would find something significant,” says Petraglia over the phone from Oxford. The hope among the researchers, as Korisettar explains, was that hidden deep in one of these caves would be a treasure trove of fossils and bones of ancient humans. The researchers, however, had no such luck.
But during this period, even as their cave excavations didn’t quite yield the desired results, Korisettar’s mind began to drift to the odd name of a nearby village he had chanced upon: Jwalapuram. Maybe, Korisettar reasoned, the name of the village—Jwala, which means ‘fire’ in Hindi—was an allusion to volcanic ash that could be buried underneath?
A few years before he began work on the cave excavations, Korisettar—while accompanying a visiting professor on a visit to a Paleolithic site at Pune’s Bori region—had discovered ash from the 74,000-year-old Toba eruption. As the two archaeologists had walked downstream along the river Kukadi that flows through that region, discussing, among other things, the nature of the river and the quality of the soil in this part of the world, Korisettar had noticed an unusual white powder-like material shining and spread out across the other side of the river. Accompanied by his friend and with his trousers rolled up, he hiked across the river to examine this strange white powder which was later dated to the Toba event.
“Everybody thought I was mad then to suggest something like this,” Korisettar says with a laugh, recalling his discovery of Toba ash in Pune. “But I was certain this was different from anything we knew in India.”
As the work in Andhra Pradesh continued, similar thoughts again began to circulate in Korisettar’s mind. He began to wonder if hidden in the depths of Jwalapuram might not be that very ash from the Toba explosion. During this period, all around the region, mining activities were yielding large amounts of volcanic ash.
“Villagers were digging up huge amounts of ash,” Petraglia says. “And the obvious questions were: where was all that ash coming from? And how old was it?”
Petraglia, Korisettar and their team of archaeologists now began to look for answers, not just in the caves of Andhra Pradesh, but below the grounds of Jwalapuram. And underneath this distant village in a forgotten part of that state, they discovered huge amounts of Toba ash, some of it as much as two metres deep. But the really big discovery wasn’t just the finding and dating of the ash. Just above this huge layer of ash were hundreds of different types of stone tools made by ancient humans. And, shockingly, underneath the 74,000-year- old layer were hundreds of other such implements. This meant that humans were already present in India all those years ago when the Toba eruption occurred. The artefacts, the researchers realised, were remarkably similar to those that have been discovered and dated back roughly to this period in southern Africa, where the only toolmakers were Homo sapiens.
“Do you realise how big this discovery was?” asks Korisettar and pauses for its significance to sink in. “This means we, modern human beings—in a complete contradiction of popular scientific opinion—had reached India, right here in fact, 74,000 years before.”
The mystery of the human story does not quite lie only in what is ahead of us. Science fiction, space travel, the brain-computer interface, bio- and nano-technology—as marvellous as these are and the mind-boggling future they promise, they are not any bigger than the big questions of our ancient past. The real story hence is not only where we are going, but where we came from. Who are we? Where did we originate? How could a handful of unremarkable bipeds from a small part of eastern Africa conquer the entire globe? What happened to our distant cousins: the Neanderthals, the Denisovans, the others that we perhaps still haven’t discovered? Did they die out on their own or did we kill them all? Or did we breed them, as some research seems to suggest? And can this, more explosively, account for how each race differs from the other at least in physical appearance?
But perhaps the most intriguing question of them all is what led us to leave our cradle, Africa, and when and how exactly did we undertake this epic odyssey. In the past few decades, discoveries in Africa, Europe and parts of South East Asia and Australia have offered us illuminating insights into this journey. But interestingly, it is here in India, in the thick ash deposits of the unknown village of Jwalapuram in southern India, where some crucial answers to our questions of human migration and evolution seem to be emerging.
The most dominant theory about the exodus of modern human or Homo sapiens from Africa is that it occurred around 60,000 years ago, long after the Toba eruption. A small group of modern humans managed to reach the Levant, either through the desert or across the sea, and from there they moved rapidly along the coast of the Arabian peninsula, India and southeast Asia, drinking fresh water from springs that have now been covered up by the seas, and reaching Australia by as early as 50,000 years ago. Along the way, small offshoots from these groups of migrants ventured elsewhere. As archaeological research has so far indicated, they were able to reach Europe not before 45,000 years ago. Researchers have attributed this relatively late arrival to Europe to the continent’s harsh cold winter and the presence of Neanderthals who had already colonised the area. Over the years, there have been significant findings like the discovery of modern human skulls and bones from Israel’s Skhul and Qafzeh caves, which have been found to be around 100,000 years old. But researchers have claimed that these were the remains of a failed migration. These were Homo sapiens, they claimed, who had left Africa long before the migration that took place about 60,000 years ago, but who couldn’t expand beyond what is now Israel. They either died out or returned to Africa. Geneticists who have analysed the DNA of modern day humans across the globe also speak of a late, rapid colonisation of the rest of the world. All research, archaeological or genetic, has so far pointed out that we are all descendants of modern humans who left Africa not before 60,000 years ago.
But what Petraglia, Korisettar and their colleagues are now discovering in India is an alternate theory entirely. Modern humans left Africa, they say, long before the hypothesised exodus of 60,000 years ago. They moved out of Africa not in one single group, but in several groups over a long period of time; and travelling not along the coast, but wandering through what are currently the deserts of the Arabian region but would have had river valleys and lake shores back then, advancing and retreating as the weather and other conditions permitted, reaching Asia at least 74,000 years ago, if not about 50,000 years earlier. This journey was slow and meandering, perhaps the result of their search for game and useful plants, rather than a rapid march of colonisation as popularly imagined.
“We have always considered the fossils found in the Israel caves [of Skhul and Qafzeh] as part of a failed migration. There have been more finds now in the Arabian region (106,000-year-old stone relics found in Oman, and stone artefacts dated to 125,000 years ago in Jebel Faya, UAE, both of which resemble those created by modern humans during that period in Africa) which puts modern humans right at the doorstep of Asia,” says Korisettar. “Why is it impossible to believe that some of them made it here in Asia?”
The Jwalapuram sites are located in the Jurreru River Valley which cuts eastwards through the Erramala Hills in Andhra Pradesh’s Kurnool district. It is a hot and dusty region, with thorny and scrubby acacia bushes, huge limestone escarpments and quartzite boulders. The river that once ran through this region is now dammed, and there are small seasonal streams that irrigate paddy fields at the edge of the basin. About 11 km away to the west is its nearest town, that of Banganapalle. There is nothing much for locals to do in this region but to work as miners scraping out volcanic ash.
But, according to Korisettar, several thousands of years ago, Jwalapuram and this region of the Jurreru River Valley would have been a verdant area. A high water table would have ensured a year-long supply of spring water gushing down the limestone hills, and the floor of the basin, fed by the rains and spring water, would have turned into a lake.
“Everything would have been here for the passing ancient humans: fresh water, green vegetation, animals, and the ideal rocks—such as quartzite, limestone and chert—to create a wide variety of stone tools,” according to Korisettar. “It would have been a great place to live. And many of them might have not had any reason to move out.”
The Jwalapuram sites have yielded, both above and below the ash layer, a rich variety of stone tools made of those very materials—quartzite, limestone and chert. Petraglia and team have found a wide variety of stone tools. They found several large and small flakes that had been shaped out of larger core stones and later retouched to produce serrated edges, used most probably, according to Korisettar, as sharp scrapers to clean animal hides or process plant material. There were also large pointy blades that could have been useful as cutting tools, and, below the ash, the researchers also found a piece of what appeared to be striated red ochre, a mineral that is known to be used for cave and body drawings, apart from used as an adhesive to stick tools together. Above the ash, Petraglia also discovered several micro-blades that could have served as tips of spears or darts.
To Petraglia, the implication was clear: modern humans reached India long before Toba erupted. “This stone technology, these tools, they are very characteristic of tools being made by modern humans during this period of time in Africa,” he says. “These findings have proved to be very controversial since we’re finding tools and being able to date them, thanks to the Toba ash, to over 74,000 years back.”
As for the micro-blade technologies found above the ash, Petraglia argues that a long-established population of modern humans in Jwalapuram then developed these new tools on their own. What this finding also reveals is that the Toba eruption wasn’t as catastrophic as imagined previously. Those who produced stone tools before the event, continued to do so afterwards. “If we were talking about settled people with agriculture, the Toba eruption would have been a cataclysm,” he says. “But what we had were probably very mobile populations of hunter-gatherers who were able to cope with all sorts of disasters.” The emergence of micro-blades after the Toba explosion, as the evidence points out, is perhaps indicative of an evolving human technology, trying to cope with harsher climatic conditions brought about by the eruption.
What about the genetic evidence which points to a late colonisation? Both Korisettar and Petraglia are dismissive of it. Genetic analysis isn’t an exact clock, according to Petraglia. “It is always give or take a few thousand years,” he says. “Also, you are basing it on the DNA samples of present-day modern humans,” Korisettar adds. “As populations moved around and vanished over thousands of years, the genetic signals of earlier settlers could have easily gone lost in time.”
The theory of a coastal route is also debated. No remains or campsites of ancient humans taking this route have ever been discovered. But these remains, proponents of the coastal theory claim, would today most certainly exist under water in the oceans. Last year, Petraglia, along with a team of researchers, published another interesting research paper. Dating pieces of ostrich eggshells that had been discovered in Rajasthan’s Katoati region, the researchers pointed out that ostriches—the only large megafauna (large animals) apart from humans to have been known to also move out of Africa—had arrived in India before 60,000 years ago. The bird is believed to have vanished from the Indian Subcontinent around 18,000 years ago.
According to the researchers, the dispersal of ostriches into western and central India—certainly taking a continental route instead of a coastal one—offers another likely route for the modern human dispersal debate. ‘Ostrich expansions into India during the Late Pleistocene [period] indicate that continental routes of dispersal into India were also possible. Predation of ostrich and use of OES (ostrich egg shells) by contemporary and prehistoric human populations indicate significant geographic overlap of humans and ostriches in Sahel-like and savannah habitats,’ the researchers write in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. ‘This suggests that the continental routes of expansion exploited by ostrich populations prior to [60,000 years ago] focused upon Sahel-like and savannah habitats, may also have been habitable to human populations and offer an alternative dispersal route…’
This search for an alternate view in the debate around the African exodus has now taken Petraglia to the Arabian Peninsula. According to him, Arabia was once an inviting lush green region filled with lakes and wild animals that would have proved an ideal pit stop for Homo sapiens dispersing out of Africa. Petraglia is now looking for ancient human fossils and artefacts, age-old lakes and river systems. So far, he has been able to locate several artefact-filled sites apart from more than a thousand ancient lakes. “We are digging up all sorts of things,” he says. “Imagine elephants in Arabia.”
A few months ago, this argument about an older exodus from Africa received a major fillip. The journal Nature described the finding of 47 modern human teeth, dated to around 100,000 years ago, spread across a cave in China’s Daoxian County in Hunan Province. Since the teeth had no radioactively decaying carbon to date, the researchers instead dated the calcite deposits in the cave and animal remains to deduce that the teeth were between 80,000 and 120,000 years old.
“There is evidence to question previous claims. But some people don’t want to accept it,” says Korisettar. “What we need is to find the missing bones of these ancient people. And I’m sure we will find it, either in India or the Arabian region.”
Korisettar claims that the researchers have been extremely lucky in being able to find the Toba ash deposits and aretefacts. But, when it comes to finding bones, they have been nothing but unfortunate.
I ask him whether finding the Toba ash and the stone tools below it based on a hunch about the name of Jwalapuram wasn’t pure luck. And a deep laughter erupts on the other side of the phone. “Yes, that was luck. Pure luck.”
The name Jwalapuram, as Korisettar explains, wasn’t based on the term ‘jwala’ or fire as he had thought. It was based, as he later learnt, on a corruption of the name ‘jola’, the Kannada term for millet.
“You see,” he says. “We need more such luck.”